Improvement in processes for coating boiler-tubes



UIIIIIIID STATES PATENT CEEIOE ROBERT RRAYTON, DAVID JUNE, AND ORATUs-s. ERENOII, OE EREMONT, OHIO.

"\ IMPROVEMENT IN PROCESSES FOR CHOATING BOlLER-TUBES.

Specification forming part of Letters Patent No. 205,038, dated June 18, i878 application filed November 2%, 1877. S

To all 'whom it may concern.- I

' Be it known that we, ROBERT BRAY'ION, DAVID JUNE, and ORATUs S. FRENCH, of Fremont, in the county of Sandusky and State of Ohio, have invented a certain new and Improved Process for Coating Steam Boiler Tubes; and we do hereby declare thatthe following is a full, clear, and complete description thereof.

The nature of this invention relates to a process for coating steam-boiler tubing; and the object of the same is to resist the corroding and scaling of the tubes.

A more full and complete description of the invention is as follows, the accompanying drawing making a part of the specification.

It is well known to builders and users of tubular boilers that the iron tubes in steamboilers, especially vertical ones, are very lia-ble to corrode at and above the Water-line, and at the connections with the heads, to such degree that after from two to three years7 use said tubes have to be replaced by new ones. This corroding ininence depends upon heat and the character of the water.

To avoid the objectionable features ofthe iron Jtubes, brass and copperhave been used in place thereof; but such tubes are, however, too eX- pensive, and it is found to be almost impossible to set them so that they will not leak, by reason of the unequal expansion of the brass or copper tubes and the iron heads in which they are secured. To avoid these objections and the destruction of the iron tubes, and to render them more durable and reliable in resisting oxidation by heat and corrosion by water than the brass or iron tubes, is the purpose of this invention, and at the same time to give the improvedv tube all the valuable features and advantages of a copper or .Y AAbrass with the strength and stiffness of the The tube is then treated with a coating of pulverized borax, or its equivalent, and again heated to a bright yellow, and is then immediately immersed in a bath of molten brass, copper, spelter, or a combination of such metals. The heated condition of the tubes permits the molten metal to penetrate the tubes, filling and closing up cells, pores, and racl/Is therein, and forming upon it a coating of the metal, rendering the tubes capable of resisting the corroding action of the heat and Water, to

which they are subjected to a greater extent than are the ordinary iron tubes, which, from the peculiar method of their manufacture, are rendered more or less imperfect, owing to the cellular and seamed condition of the tubethus made. Finished and used in this state, they are readily destroyed when acted upon by the heat and water in a steam-boiler 5 but after the tube has been treated or coated by the process set forth, it is rendered more dense and compact, andis abetter conductor and radiator of heat, and at the same time the tube is less liable to form scale or incrustations of lime or impurities of the water, as in the case of ordinary tubes.

The iron tubes thus treated are found to be toughened, and not liable to crack and split in setting them, as their softened and toughened condition allows them to readily expand; hence there occurs no loss by ruptures in this operation.

It will be obvious that tubes made or treated in the mode above described add to the durability and safety of a boileorsteam-generor using them, without adding materially to itrY first cost.

Iron tubes treated by the process set forth have all the material advantages of thosev made of brass or copper, being less corrosive and more durable than iron, Without the disadvantage of being aifected by an unequal expansion of tubes and heads, peculiar to copper and brass tubes when used in connection with iron heads.

It is not new to coat metallic sheets and tubes with a non-corroding metal by iirst ap plying a suitable IluX and then immersing in v What We claim as our invention7 and desire to secure by Letters Patent, is-

The Within-described process for coating boiler-tubes of iron or steel, consisting in first heating` them to a red heat, then covering them with pulverized borax, again heating them to a lYellow heat, and finally subjecting them to a bath of non-corroding metal, forthe purpose of saturating as well as coating them,

all substantially as and for the purpose described.

ROBERT BRAYTON. DAVID JUNE. Y ORATUS S. FRENCH.

Witnesses:

M. E. TYLER, FRANK BRAYTON. 

